Sand blasting machine



May 17, 1932. F. H. WOLEVER SAND BLASTING MACHINE Original .Filed Feb.4, 1924 m m m m Patented May 17, 1932 FRANKLIN H, WOIIEVER, OF CHICAGO,ILLINOIS SAND BLASTING MACHINE Original application filed February 4,1924, Serial No. 690,387. Divided and this application filedOctober Thisinvention relates to improvements in sand blasting apparatus of thattype that employs air at a high pressure as a medium of propelling sandor other abrasives at high velocity through a. nozzle against metallicor any other substance to be treated.

Among the common faults with sand blast apparatus now in commercial usemay be summed up the following; lack of positive sand flow, which causesintermittent volume variations of sand flow and varying velocities;inconveniently located manual controls remote from operative points;lack of proper provisions for ready access to vital parts of theoperative mechanism to remove obstructions; lack of' means forestablishing sand flow after the sand blast has been shut off withoutexperimentation with the sand and air valves, and inconvenient means forfilling the sand tank after it has been emptied.

The various features of novelty whereby my invention is characterizedwill hereinafter be pointed out with particularity in the claim; but,for a fullflunderstanding of my invention and of its objects andadvantages, reference may be had to the following detailed descriptiontaken inconnection with 'A the accompanying drawings, wherein:

Figure 1 is a vertical central section through an apparatus arranged inaccordance with my invention, only the end portions of the tank beingshown; Fig. 2 is a section on line 22 of Fig. 1; and Fig. 3 is asection, on an enlarged scale, on line 33 of Fig. 1.

Referring to the drawings H is a sand tank to which clean sand isdelivered through a pipe 12; the sand first entering a. receivingchamber H at the top of the tank. The sand is fed in the operation ofthe machine through the hopper bottom of the tank and through asandmeasuring'apparatus J and thence through the nozzle hose K to themanually operated jet nozzle K by which the blasting sand is directed atsuitable velocity and volume onto the work.

Said pipe 12 leads tangentially into the side of the receiver, as shownin Figs. 1 and 2. The speed of the sand thereby is reduced and the sandis agitated as it enters the said receiver by impact against a series ofradial Serial No. 310,412.

trolled by a cone shaped valve 56, which controls the flow of sand fromthe receiver to the tank. Said valve is vertically movable and seatsupwardly against a ring 57, which, as herein shown, iswithin' the to ofthe tank H in axial alignment with the receiver and constitutes acontinuation thereof. The ring is fixed in any suitable manner to thetop .wall it of said tank, and its lower seating face is formed by anannular tapered body of resilient substance 58, such as rubber, toproduce an. air tight joint between the conevshaped valve and said'seat,fora purpose presently to appear. The said valve has a vertical stemwhich extends upwardly through a tubular guide'60 carried by a spiderwithin the receiver,and through a neck 61 having'at its upper end a stemguide 62. n expansion spring .63'is interposed between an upper face onsaid neck and a shoulder 64 on the stem above the neck (formed by athreaded nut) and acts normally to hold the cone-like valve againstitstapered seat.

A discharge outlet 66 at the upper end of said neck'permits dust andlight particles from the'agitated sand in said receiver to be withdrawnif a suitable suction device is connected to the outlet. Thus the sandis subjected to a final cleaning action before it is discharged intothefsand tank. When the sand tank is to be filled, the jet pump is setin operation to raise the sand from the sand pit into the receiver H andthe agitation of the sand as-it enters the receiver, due .to its impactagainst the wings 55, serves to allow the speed of the sand and to causethe sand to drop by gravity and the dust and lighter particles to beseparated from the sand by the action of the draft of air through thepipe 66, due to the low pressure in the chamber C, so that the sand isprepared in readiness for entrance into the tank in a cleanly condition.1

The seating strength of the spring 63 can be so regulated, as by the nut64, that a given weight of sand overcomes it and opens the cone-likevalve to allow the sand to flow by gravity into the tank below. The saidspring 63, regulated as it is, cooperates with gravity to control thesand flow until the tank has been filled, and after the operation of thesand jet pump has been stopped, the. .said spring acts to hold the valvehard against its seat to provide a joint against the escape of airthrough the filling valve thus described during the sand blastoperation.

An air vent is established from the tank while the tank is-beingfilledthrough a vent pipe 68', the top of which opens near the top wall ofth'etank. Said vent pipe extends downwardly through the hopper bottom of thetank and is provided exteriorto the tank with a branch 69 whichdischarges into the air. As herein shown, and for a purpose hereinafterto be described, the said branch opens into a chamber 7 O, which can befastened to the tank structure. Said chamber is provided at its bottomwith an outlet or vent opening 71 which is adapted to be open when thesaid tank is being filled, so as to equalize the tank pressure with theoperating pressure. To this end, the vent or equalizing pipe extendsbeyond the outlet branch 69 to form an extension for a purpose presentlyto appear.

After the sand tank is filled, the sand is discharged in measuredquantities therefrom through the nozzle K under the control of asuitable volume and pressure control means.

The embodiment of said control means illustrated is made as follows:

75 designates a rotative measuring bowl which is axially below thedischarge nozzle 76 of the sand tank at the conical lower end of thetank. As shown, the nozzle is formed as an integral part of the casing77 of a meas uring device and the smaller discharge of the said tank isflanged for attachment to the upper flattened end of said casing, withthe tank discharge h in line with said nozzle. The

measuring bowl is fixedto and rotates with a vertical stub shaft 78which 1s rotatively mounted in a bearing 79 that is carried by and ispartly enclosed in a shell 80 of suitable form to protect said hearingfrom dust and sand. The bearing is further protected at the point wherethe hub of the bowl and the bearing members meet by a skirt 80 which isarranged in overlapping relation to the upper conical end of said shell80. Fixed to the lower end of said shaft 78 is a beveled gear wheel 81thatmeshes with a beveled pinion 82. Said pinion is fast to the innerend of a shaft 83 that is mounted to rotate in a bearing 84 which iscarried by the casing 77. The lower, tapered end 85 of the measuring thenozzle K.

chamber 104 of said casing.

device casing has the form of a neck 86 that can be made integral with afitting 87, herein shown to be the casing of a sand pump, through themedium of which sand is delivered from the measuring device casing tothe sand discharge tube and nozzle, as will hereinafter be described.

The shaft 83 is fixed to a worm gear 88 which meshes with a worm 89 thatis fixed to and rotates withthe shaft of an air turbine 90. Said wormgears are enclosed in a suitably shaped sand proof casing to protectthem from sand and dust. 91 designates the casing of the air turbine 90,one side of which casing is open to one branch 106 of a pressure pipe92. Saidpipe 92 has a flanged, axial connection atits lower and with thetapered receiving end 93 of the said pump casing 87., there being apressure chamber 9 1 formed in said tapered formation 93 between theadjacent end ofthe pipe 92 and a transverse wall or portion 95 in saidsand pump casing87.

Connected to theend of the pipe 92; remote from the sand pump isa pipe97 for "deliveringair under pressureto the pipe 92, for

the. double purpose of furnishing air to operate the turbine and foroperating the sand pump by which the sand is forced through Said pipe 97has a cut-ofi and controlling valve 98. The pipe 97 commun icates withthe pipe 92 through one lateral branch of a fitting 99, another branchof the fitting being connected directly to the conduit 92. Said fittingis valve controlled to shut ofl air pressure from the pipe 97 whenthe'sand tank is being filled and when the blasting operation isdiscontinued. A valve 100 for this purpose is shown as being closed.

Said valve 100 is a tapered faced closure to engage alike-shaped seat ina diaphragm of the fitting 99. The stem 101 of said valve extendsthrough a stuffing box at the top of the fitting, and is connected by acoupling 102 with the lower end of a stem 103. The stem 103 extendsupwardly through a chamher 104 made of upper and lower casing membersand is connected to a diaphragm 105 which extends across said chamber,with the margin thereof confined between the margins of the members ofthe two part casing ina known manner. Said stem 103 extends through astuffing box in the lower casing member to maintain air tight in thelower The stem is surrounded in its part between said dia phragm andthetop member of the casing by a spiral expansion spring 107 the normaltendency of which is to closesaid valve 100. The upper end of the stem103, above the casing 10 1,'carries a disc valve 103 to close the ventopening 71 in the equalizing chamber 70 before referred to.

Located within the conduit 92, abreast the air turbine, is a partition105 which is free at its upper and'lower ends from the conduit wall and,in efiect, provides two branch conduits 106, 107, the former of whichdirects air to the vanes of the turbine, and the latter of which shuntsair from the turbine blades and directs it to the sand pump beneath themeasuring mechanism. The said branches 106, 107 are adaptedto beseparately controlled to vary the volume of air passing therethrough byany suitable control or throttle means such, for instance, as by meansof studs 108, 109 that are threaded through the opposite walls of theconduit and are adapted at their inner ends to approach and recede fromthe partition 105.

The sand pump embraces, in addition to the parts already described, atube 110 which lies axially within the casing 87 and is fixed at itsrear end in a central opening in the partition 95. Said tube, therefore,affords free passage for air centrally through the pump chamber. Thesand falls around the tube 110 in front of the partition 95. Saidpartition has in its lower part a plurality of openings 112. Air, underpressure, therefore, passes through said tube and through said openings112 and acts with an aspirator effect to forcibly discharge the sandfrom the pump casing through the nozzle. The nozzle has a restrictedthroat near its outer end afforded by a liner 114 made of a substance toresist wear. The said liner is flare-d at both ends and restrictedbetween its ends so as to thereby impose a resistance to sand dischargeand to increase the velocity of the sand projected from the nozzle.

Located at, and preferably carried by the nozzle piece is a cut-off andcontrol valve, designated as a whole by 115. As shown, its casing isprovided with a collar 116 which is clamped about the hose K at thepoint where it laps over the nozzle piece K to thereby fasten the valvein place and to clamp the hose on the nozzle piece. The casing of saidcontrol valve is formed with three tubular branches 117, 118, and 119.The branch 117 opens to the atmosphere. The

branch 118 is connected by a flexible hose 120 and a pipe 121 with thelower chamber 104 of the diaphragm casing 104. The branch 119 isconnected by a flexible hose 122 and a pipe 123 with the main pressurepipe 97 just inside its valve 98. 124 is a plug that is rotativelyseated in said casing and is provided with an actuating handle 125. Saidplug is provided with two curved internal ports 126, 127, the ends ofwhich are spaced angular distances apart equal to the angular spacingsof the ports in the branches of the casing, the spacings being 90 asherein shown.

In the adjustment of the parts as shown, the lower chamber 104 of thediaphragm chamber 104 is open, through the port 127 in the plug, toatmosphere, so that the spring thereby to the air turbine and the sandpump.

Such air line pressure is also operative to closethe valve disc 103against the sand tank vent opening 71. These are the operative positionsof the parts for sand blasting. 128

designates a branch I which leads from the extension of the equalizingpipe 68 and communicates with the casing 77 enclosing the sand volumecontrol mechanism, where pres sure in-said casing and the tank can beequalized .during the sand blasting operation of the machine. J

It is desirable that means he provided for limiting the effect of thesand head in the tank H, so as to thereby reduce the feed velocity ofthe sand from said tank to the measuring device. This result can beefiected by arranging a cone-like shelf or diaphragm 180 within the sandtankabove its discharge nozzle 76, and supporting it centrally in saidtank by brackets 131 from the wall of the tank.

This central "support or shelf will modify the flow line of the sand inthe manner indicated in the drawings, and reduce the head pressure ofthe sand at the outlet nozzle to an extent represented by the area ofsaid shelf.

In order that free access may be had to the outlet of the tank to removeclogging obstructions, a hood 132 is arranged below said shelftransversely across the conical lower end of the tank. The hood can besupported on opposite walls of the tapered portion of the tank. Atoneend of said hood the tank wall is provided with a hand hole 133,covered by a suitable closure. Through the hand hole any suitableimplement can be inserted into the restricted outflow of the tank toclear the outflow of any obstruction that may lodge there. The presenceof said hood, to the extent that its side margins intercept the normalflow line from the margins of said shelf 130 further reduces the sandhead pressure at the tank outlet. j

I To start sand blasting, the compressed air valve 98 is turned on andthe operator takes the nozzle K in his hand and turns the control valveplug to a suitable stop (not shown) which registers the port 126 withthe proper casing ports to connect the pressure pipe 97 to the chamber104 beneath the diaphragm.

The increased area. of surface of the diaphragm over the net surface ofthe valve causes the valve 100 to lift and to thereby compress spring.107and to also cause the disc valve 103 to seat against and close thevent port 71 through which the tank pressure was theretofore equalizedwith atmosphere.

The sand tank is now sealed ofi from the atmosphere and compressed airnow flows 5 through valve 98 through the opening controlled by the valve100, and thence through the branch passages 106 and 107 of the conduit92. A portion of the air. is passed through the passage 106'over thevanes of 10 the turbine to drive the same and another portion isdiverted through the branch pas- "sage 107 to the chamber 94 at the rearof the nozzle sand'pump, and thence through nozzle hose K and the nozzleK. The air pressure I5 built up in the chamber 94 of the sand pumpcarries the sand deliveredto the pump casing through the hose anddischarges it fromnozzle K onto the work.

The small area of the nozzle K as compared tothe area of intake airpassages 110, 112 builds up pressure in chambers 94 and 77, which issoon equalized in the tank by flow of air from said chamber 77 through,

the equalizing branch 128 and pipe 68 to the tank. This pressure alsoserves to seat the sand feed control cone: valve 56 more tightly than bythe action of the spring 63 alone. As soon as pressure is equalized inthe tank, the casing 77 and the said pump, sand will begin to flow fromthe tank onto cup 75, which is being driven by the turbine '90 at a rateof speed due to the control of the branch 106 which delivers air to saidturbine. Rotation of the bowl acts to centrifugally throw the sanddelivered thereto outwardly and cause it to fiow to the restrictedoutlet or passage of the casing 77, from whence itis forced to thedischarge or blasting nozzle K. Obviously the more rapidly the bowl isrotated the greater will be the volume of sand delivered down throughthe nozzle 76 of the sand tank. The control of the speed of this bowl,through controlling its driving turbine by the ac- 45 tion of the valve109 or equivalent throttling means, has the effect to vary the volume ofsand delivered to the sand pump below in a given time. Likewise, theoperation. of the valve 108 or an equivalent control for the highpressure branch 107 serves to control the velocity at which air isdelivered to the chamber 94 of the sand pump. With 97 to the conduit 92and to the pressure chamber 104- of the diaphragm casing and to Whensand from the tank H has been exhausted, the valve 115 at the nozzle Kis turned by its handle 125, so as to close communication from the feedor pressure pipe establish communication from said diaphragm chamber 104to the atmosphere. The spring 107 then becomes active on the diaphragmto close the valve 100 and to open the equalizing port 71 so as toequalize the pressure in the tank with the atmosphere. The tank H isthen charged through the pipe 12, after which the hand valve 115 isadjusted to open the valve 100 to connect the feed pressure pipe to theconduit 92, whereupon the machine is again in position for sand blastingoperation. 7

The present application is a division of my prior application SerialNumber 690,387 85 filed February 4:, 1924.

A sand blasting apparatus comprising a storage tank for blasting sandprovided with a discharge opening, a sand pump to receive sand from saiddischarge opening, a hose connected with the discharge end of said pump,a jet nozzle connected to the free end of said hose, a pressure airline, a conduit connecting said, air line to the inlet side of said'sandpump, a pressure closed valve in said conduit to cut off air pressure tosaid sand pump, a diaphragm connected to said latter valve, a casing toenclose it, and a manually controlled valve connected to said air lineand to said casing and adapted in one adjustment to transfer pressurefrom the air line to said casing below said valve diaphragm to open theair line valve against the pressure of said line and in anotheradjustment close the air line to said diaphragm casing and to open saidcasing to the atmosphere.

In testimony whereof, I sign thisspecification.

FRANKLIN H. WOLEVER.

these controls it will be obvious that the sand I can be accuratelyvaried to suit different kinds of work. With a constant feed pressure inthe pipe.97 it will be obvious that the valves 108 and 109 will permit aconsiderable range of relative volume and velocity of air delivered tothe turbine and to the pump through the branches 106, 107, with acorresponding variation, as stated, with respect to the volume andvelocity of the sand discharged from the nozzle K onto 65 the work.

volume and velocity discharge at the nozzle

